Awaiting him are investigators from the Naval Criminal Investigation Services who are probing every aspect of his disappearance June 21 from a base near Fallujah, a center of resistance by both Baathists and Islamic militants to the US-led occupation.

"What a missing persons investigation does is simply looks at everything that occurred or might have occurred that resulted in an individual becoming missing," Major Jason Johnston, a US Marine Corps spokesman said.

"It takes everything into account, whether he left on his own, whether he was captured, whether he was lured. All those things will be looked at," he said.

A US defense official, who asked not to be identified, told AFP that Hassoun maintains he was abducted.

The official, however, said suspicions have not been put to rest that the Lebanese-born Hassoun deserted to return to relatives in Lebanon, and that the saga of his capture and a videotaped threat to behead him were a ruse to aid in his escape.

NBC News, citing US officials, reported Tuesday that Hassoun left behind a cellphone which revealed he made a series of phone calls to relatives in Lebanon shortly before he disappeared. A Marine spokesman would not comment.

Hassoun was supposed to have flown from Ramstein Air Base in Germany to the United States Wednesday, but the flight was delayed for a day because of mechanical problems with his aircraft, Johnston said.

He will go to the Marine Corps base at Quantico, Virginia, near Washington, rather than to Camp Lejeune, North Carolina, where his unit, the 2nd battalion of the 2nd Marine Division, is based, he said.

"It allows access for various agencies that need access to him," including the Naval Criminal Investigative Service, said Johnston.

"The repatriation process is a phased approach to returning the service member to society. The length of this process can vary from weeks to months, depending on the circumstances of the individual case," the Marine Corps said in a statement.

Accompanying Hassoun is a repatriation team of psychologists and other officials responsible for his debriefing.

"I'm in good health and spirits," Hassoun said Wednesday as he left Landstuhl, the largest US military hospital outside the United States.

"All thanks and praise are due to God for my safety," he added.

When he was admitted on July 9, Hassoun had no bruises on his body but was exhausted and had lost about 10 kilogrammes (22 pounds) in weight.

Hassoun's disappearance first came to public attention on June 27 when the Dubai-based Arabic news channel Al-Jazeera broadcast a videotape showing Hassoun facing the camera, blindfolded and head bowed beneath the blade of a sword.

A group calling itself "Islamic Retaliation Movement - Armed Resistance Wing," claimed to have abducted Hassoun after "infiltrating a US military base in Iraq" and warned it would execute him unless all detainees were freed from coalition prisons in Iraq.

The claim followed the gruesome televised beheading of US businessman Nicholas Berg the previous month and came amid a rash of other hostage takings.

But the New York Times on June 30 quoted a Marine official as saying that Hassoun, an Arabic speaker who was working as a translator at the base, had deserted his post in shock after seeing one of his sergeants blown apart and was heading to his native Lebanon when he was kidnapped.

The Marine official said Iraqis Hassoun had befriend on base promised to help him but turned him over to his kidnappers.

The same day, however, Hassoun's status was changed from "missing- whereabouts unknown" to "captured."

Four days, later a message posted on an Islamic website claimed he had been beheaded.

The statement from the "emir of the army of Ansar al-Sunna, Abdallah Al-Hassan ben Mahmoud" to US President George W. Bush said Hassoun had "romantic relations with a young Arab girl and was lured away from his base."

But the US military said on July 4 there was no credible evidence that a marine had been beheaded, and then the Ansar al Sunna group denied making the statement that appeared on the Islamic website.

Al Jazeera reported the following day that Hassoun had been freed and "taken to a safe place" after he promised not to go back to the US military.

One of Hassoun's brothers in Lebanon on July 6 said he had received a call assuring him that Hassoun was alive and had been freed. The Lebanese foreign ministry said its embassy in Iraq had informed it that Hassoun was in a safe place.

Hassoun then turned up in Beirut where he turned himself over to the US embassy on July 8.

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